As a power inverter circuit which converts a DC power into an AC power, bridge inverters have been known widely. As bridge inverters of this kind, Non Patent Literature 1 discloses single- and three-phase inverters.
A single-phase bridge inverter comprises first and second switching elements sequentially connected in series between input terminals on higher and lower voltage sides and third and fourth switching elements sequentially connected in series between the input terminals on the higher and lower voltage sides. By alternately turning on a set of the first and fourth switching elements and a set of the second and third switching terminals, the single-phase bridge inverter generates a single-phase AC power between an intermediate node of the first and second switching elements and an intermediate node of the third and fourth switching elements (e.g., FIGS. 6 and 9 of Non Patent Literature 1).
On the other hand, a three-phase bridge inverter comprises first and second switching elements sequentially connected in series between input terminals on higher and lower voltage sides, third and fourth switching elements sequentially connected in series between the input terminals on the higher and lower voltage sides, and fifth and sixth switching elements sequentially connected in series between the input terminals on the higher and lower voltage sides. By periodically turning on a set of the first and fourth switching elements, a set of the third and sixth switching elements, and a set of the fifth and second switching elements with a phase difference of a ⅓ cycle therebetween, the three-phase bridge inverter generates a three-phase AC power among an intermediate node of the first and second switching elements, an intermediate node of the third and fourth switching elements, and an intermediate node of the fifth and sixth switching elements (e.g., FIGS. 7 and 10 of Non Patent Literature 1).
Non Patent Literature 1 also discloses a bridge inverter which performs switching control by using a pulse width modulation (PWM) scheme during a period when the switching elements in each set are on (e.g., FIG. 13 of Non Patent Literature 1).    Non Patent Literature 1: IMAI Koji, Power Electronics Handbook (R & D Planning Co., Ltd., February, 2002), p. 328-337